1. Field of the Invention
The present invention relates to a tape-like or sheet-like highly heat conductive insulating member used in an electromagnetic coil of an electromagnetic device such as a power generator, electric motor or transformer, and a method of manufacturing the insulating member. The present invention further relates an electromagnetic coil manufactured employing a high-heat conductive insulating member.
2. Description of the Related Art
In order to improve an electromagnetic device, that is, to achieve a higher efficiency, a smaller size and a lower production cost, it is necessary to improve the cooling performance of its electromagnetic coil. Here, one of the measures to improve the cooling performance of the electromagnetic coil is that the electro-insulating tape and sheet material used for a peripheral member of the electromagnetic coil should be made into a high heat conductivity type.
The heat conductivity of a conventional electro-insulating member is about 3 to 37 W/mK. Jpn. Pat. Appln. KOKAI Publication No. 11-71498 discloses that the components of the matrix resin are changed to increase the amount of the filling material, as its object, that is, increasing the heat conductivity of the electro-insulating member. However, the heat conductivity of the electro-insulating member of this prior art document is not sufficient, and further the resins that can be employed for this reference technique are limited to special components only.
Jpn. Pat. Appln. KOKAI Publication No. 2002-93257 discloses a highly heat conductive mica matrix sheet having a backing member containing inorganic powder, as the electro-insulating member used for an electromagnetic coil. However, in the insulating member of this prior art document, the heat conductive material that is used for the backing member does not exhibit a sufficiently high heat conductivity. Thus, as an insulating layer of an electromagnetic coil, the heat conductivity is not sufficient.
Jpn. Pat. Appln. KOKAI Publication No. 11-323162 is directed to an improvement of the heat conductivity of an insulating layer, and discloses that the heat conductivity of the resin can be improved by using a crystalline epoxy resin as the resin for the insulating layer. However, the crystalline epoxy resin of this prior art document is in a solid state at room temperature, and therefore it is difficult to handle it.
Jpn. Pat. Appln. KOKAI Publication No. 10-174333 discloses an electromagnetic coil in which heat conductive sheets are alternately wound around a wire-wound conductor, for the object of improving the heat conductivity of an insulating layer. However, in the electromagnetic coil of this prior art reference, the heat transmission is insulated by the mica layer, and therefore it is difficult to achieve a high heat conductivity.
As described above, the conventional insulating members entail such drawbacks that a sufficient heat conductivity cannot be obtained and the production takes much labor, time and high cost.